JP2006000720A - Gas separation method and apparatus for vapor mixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for stabilizing the supply side pressure of a separation membrane module, in the method and the apparatus for separating and recovering a gas mixture containing a vapor mixture, using the gas separation membrane module. <P>SOLUTION: In this gas separation method, the gas mixture containing the vapor mixture is supplied to the supply side of the gas separation membrane module, at least a first vapor in the gas mixture containing the vapor mixture is made to selectively permeate, and the gas mixture is separated into a permeating flow with the highly concentrated first vapor and a non-permeating flow with the low concentrated first vapor, and recovered. The non-permeating flow from the gas separation membrane module is introduced into a pressure regulating tank through a condenser which is provided with a pressure regulating means by the input and output of atmospheric gas. The pressure regulating means stabilizes the supply side pressure of the separation membrane module. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, the gas mixture containing the vapor mixture is supplied to the supply side of the gas separation membrane module, and at least the first vapor in the gas mixture containing the vapor mixture is selectively permeated to increase the concentration of the first vapor. A gas separation method for separating and collecting a permeate flow and a non-permeate flow in which the first vapor is reduced in concentration, wherein the non-permeate flow from the gas separation membrane module is introduced into the pressure regulating tank through a condenser, and The pressure regulating tank is provided with a pressure adjusting means by taking in and out the atmospheric gas, and relates to a gas separation method and a gas separation apparatus thereof, wherein the pressure adjusting means stabilizes the supply side pressure of the separation membrane module.

In Patent Document 1, an aqueous solution containing an organic substance is vaporized by an evaporator to generate a gas mixture containing organic vapor and water vapor, and the gas mixture is contacted with a gas separation membrane to selectively permeate water vapor. Discloses a method of dehydrating and concentrating organic matter, and then cooling and condensing the organic vapor dehydrated and concentrated and recovering it in a product tank.
In this way, the liquid mixture is vaporized by the evaporator and supplied to the gas separation membrane as a gas mixture containing the vapor mixture, and the first vapor of the vapor mixture is selectively permeated to increase the concentration of the first vapor. And the non-permeate flow in which the first vapor is reduced in concentration, and then the non-permeate flow in which the first vapor is reduced in concentration is cooled and condensed to be recovered as a liquid, the liquid to be supplied or agglomerated and recovered Since it is difficult to avoid pressure fluctuations due to the instability of the liquid in and out of the system and the vaporization process and the condensation process, it is difficult to stabilize the pressure on the supply side (non-permeation side) of the gas separation membrane. Since the permeation rate of a specific component in a gas separation membrane depends on the partial pressure difference between the gas components on both sides of the separation membrane, the permeation rate fluctuates each time a pressure fluctuation occurs on the supply side (non-permeation side) of the gas separation membrane. Therefore, it becomes difficult to separate and collect with high accuracy. For this reason, a separation and recovery method that suppresses pressure fluctuation has been demanded.

JP-A-5-177111

  In the present invention, the gas mixture containing the vapor mixture is supplied to the supply side of the gas separation membrane module, and at least the first vapor in the gas mixture containing the vapor mixture is selectively permeated to increase the concentration of the first vapor. A gas separation method for separating and collecting a permeate flow and a non-permeate flow in which the first vapor is reduced in concentration, wherein the non-permeate flow from the gas separation membrane module is introduced into the pressure regulating tank through a condenser, and Provided is a gas separation method and a gas separation device characterized in that the pressure regulating tank includes pressure adjusting means by taking in and out the atmospheric gas, and the supply pressure of the separation membrane module is stabilized by the pressure adjusting means. With the goal.

In the present invention, the gas mixture containing the vapor mixture is supplied to the supply side of the gas separation membrane module, and at least the first vapor in the gas mixture containing the vapor mixture is selectively permeated to increase the concentration of the first vapor. In the gas separation method of separating and recovering the permeate flow and the non-permeate flow in which the first vapor is reduced in concentration, the non-permeate flow from the gas separation membrane module is led to the pressure regulating tank through a condenser, and the pressure regulation The tank is provided with a pressure adjusting means by taking in and out the atmospheric gas, and the pressure adjusting means stabilizes the supply side pressure of the separation membrane module.
Furthermore, the present invention supplies a gas mixture containing a vapor mixture to the supply side of the gas separation membrane module, selectively permeates at least the first vapor in the gas mixture containing the vapor mixture, and the first vapor has a high concentration. In the gas separation device for separating and recovering the permeated flow and the non-permeated flow in which the first vapor is reduced in concentration, the non-permeated flow from the gas separation membrane module is led to the pressure adjusting tank through the condenser, and The pressure regulating tank includes a pressure adjusting means by taking in and out the atmospheric gas, and relates to a gas separation apparatus configured to stabilize the supply side pressure of the separation membrane module by the pressure adjusting means.

  In the present invention, the liquid mixture is vaporized by an evaporator to form a gas mixture containing a vapor mixture, the gas mixture is supplied to a gas separation membrane, and the first vapor of the vapor mixture is selectively permeated so that the first vapor is Even when the permeate stream having a high concentration is separated into the non-permeate stream in which the first vapor is reduced in concentration, and then the non-permeate flow in which the first vapor is reduced in concentration is cooled and condensed and recovered as a liquid, it is more convenient. The apparatus can easily suppress pressure fluctuations, stabilize the supply side pressure of the separation membrane module, and perform gas separation and recovery.

FIG. 1 is a flowchart for explaining the outline of the gas separation method of the present invention. Hereinafter, description will be given with reference to FIG.
In FIG. 1, the liquid mixture is supplied to an evaporator 2 equipped with a heater 3 at the bottom. In the evaporator 2, the liquid mixture is heated by the heater 3 to generate a vapor mixture. The vapor mixture is supplied to the gas separation membrane module 5 together with the atmospheric gas. The gas mixture composed of the supplied vapor mixture and the atmospheric gas flows while contacting the gas separation membrane on the supply side (non-permeation side) of the gas separation membrane module 5, while the first vapor selectively permeates the separation membrane. Then, the first steam is separated into a permeate stream 6 having a high concentration and a non-permeate stream 7 in which the first steam has a low concentration. The permeate stream 6 and the non-permeate stream 7 are discharged from the gas separation membrane module 5, respectively. The non-permeate flow 7 discharged from the gas separation membrane module 5 is cooled and condensed by the condenser 8, and the vapor component is liquefied to become liquid and atmospheric gas. Next, the liquid and the atmospheric gas are guided to the pressure regulating tank 9. The liquid is stored in the pressure regulating tank 9, and is discharged from the pressure regulating tank 9 as necessary. In the present invention, the pressure regulating tank 9 is provided with pressure adjusting means 10 (enclosed by a broken line) by taking in and out the atmospheric gas. In the case of FIG. 1, the pressure adjusting means 10 includes a pressure adjusting valve 12 and a back pressure adjusting valve 13 for adjusting pressure in a conduit 11 that supplies and discharges atmospheric gas. The pressure regulating tank 9 is configured to communicate with the pressure regulating tank 9 by a conduit 14 branched from a conduit between the back pressure regulating valve 13 and the back pressure regulating valve 13.

  In the gas separation method of the present invention, the pressure on the supply side (non-permeation side) of the gas separation membrane module is reduced due to instability in the supply / removal of the liquid to be supplied or the liquid to be recovered by cooling and condensation, and the vaporization process or the cooling condensation process. Even when affected, the pressure adjustment means 10 suppresses pressure fluctuations and stabilizes the pressure on the supply side (non-permeation side). Specifically, when the pressure on the supply side (non-permeate side) of the separation membrane module is lower than a predetermined pressure, the pressure in the pressure adjusting tank 9 is also reduced, but is pressurized by the pressure regulating valve 12 and maintained at the predetermined pressure. On the other hand, when the pressure on the supply side (non-permeation side) of the separation membrane module increases above a predetermined pressure, the pressure in the pressure regulating tank 9 also increases, but is reduced by the back pressure regulating valve 13 and maintained at the predetermined pressure.

  That is, in the present invention, the non-permeate flow (gas mixture containing steam) from the gas separation membrane module is liquefied by the condenser, led to the pressure regulating tank, stored in the pressure regulating tank, and as necessary. In the series of flows discharged from the pressure adjustment tank, the pressure adjustment means by taking in and out the atmospheric gas branched from the flow suppresses the pressure fluctuation on the supply side (non-permeate side) of the gas separation membrane module and stabilizes it. It has become.

  In the gas separation method of the present invention, the liquid mixture is supplied to the evaporator intermittently or continuously. The liquid mixture is heated and vaporized by the heater of the evaporator and mixed with the atmospheric gas to become a gas mixture. In the vaporization, it is preferable to control the amount of the liquid mixture in the evaporator of the liquid mixture and the degree of heating of the evaporator so that a certain amount of the vapor mixture is supplied to the separation membrane module. Normally, the liquid feed pump is controlled by the liquid level controller of the evaporator so that the amount of liquid mixture in the evaporator is kept constant, and the heater temperature is controlled by the temperature controller in order to keep the evaporation amount of the evaporator constant. Control.

  In the gas separation method of the present invention, the gas mixture containing the vapor mixture is preferably superheated (superheated) by a heating means (superheater) before being supplied to the gas separation membrane module. The superheat is to prevent the vapor mixture from condensing during the treatment with the gas separation membrane module, so that the temperature becomes about 2 to 3 ° C. or more, preferably 5 ° C. or more higher than the vapor temperature vaporized by the evaporator. Is preferable. In the case of superheating, it is preferable to control the superheater by measuring the temperature of the gas mixture after superheating in order to keep the temperature of the gas mixture constant.

  In the gas separation method of the present invention, the temperature and pressure of the gas mixture containing the vapor mixture and the atmospheric gas supplied to the gas separation membrane module are determined by the type of steam and the amount of treatment, but are usually 50 to 250 ° C., preferably 80 ° C. ˜200 ° C., particularly 80˜150 ° C., 0.01˜1 MPa (absolute pressure), preferably atmospheric pressure˜0.6 MPa (absolute pressure). Further, it is preferable that the gas separation membrane module is heated to a similar temperature so that the temperature of the supplied gas mixture is maintained. It is preferable that the gas separation membrane module and the pipe leading to the condenser are kept warm with a heat insulating material or the like so that condensation does not occur in front of the condenser.

  In the gas separation method of the present invention, the non-permeate flow obtained from the non-permeate side of the gas separation membrane module has a reduced concentration of the first vapor as a result of the first vapor selectively permeating the gas separation membrane (second vapor). Is a gas mixture containing a vapor mixture. This gas mixture is introduced into a condenser having a cooling function, and the vapor component is liquefied and sent to a pressure regulating tank. The separated and recovered liquid is a liquid mixture in which the concentration of the first vapor component is reduced (the concentration of the second vapor component is increased), and is stored in the pressure adjustment tank, or further to a storage tank connected to the pressure adjustment tank. Sent and stored. In the process in which the liquid mixture is accumulated in the pressure adjusting tank or the storage tank, the space on the supply side (non-permeation side) of the gas separation membrane module communicating with the pressure adjusting tank or the storage tank has a volume of space due to an increase in the amount of liquid. Since the pressure decreases, the pressure increases, but the pressure is kept constant by the pressure adjusting means (the closed back pressure adjusting valve 13 in FIG. 1 is opened). Further, when a predetermined amount of the liquid mixture is accumulated in the pressure adjusting tank or the storage tank, the liquid mixing unit is extracted from the pressure adjusting tank or the storage tank. In this process, the space on the supply side (non-permeation side) of the gas separation membrane module communicating with the pressure regulating tank or the storage tank is reduced in pressure because the liquid volume decreases and the volume of the space increases. The pressure is kept constant by the pressure adjusting means (the closed pressure adjusting valve 12 is opened in FIG. 1).

  In the gas separation method of the present invention, the permeation side of the gas separation membrane module is reduced to about 0.01 to 70 kPa (absolute pressure), particularly about 5 to 70 kPa (absolute pressure) by an ejector or a vacuum pump, and / or It is preferable to flow a sweep gas for sweeping the permeate gas from the space on the permeate side of the separation membrane. Further, the permeate flow from the gas separation membrane module may be connected to another pressure regulating tank via a condenser, and the pressure regulating tank may stabilize the permeation side pressure of the separation membrane module by pressure adjusting means. The permeate flow in which the first vapor obtained from the permeation side of the gas separation membrane module has a high concentration is preferably liquefied by a condenser having a cooling function and stored in a pressure-regulating tank or a storage tank.

  The sweep gas may be any gas as long as it does not contain the first vapor. For example, the sweep gas is a gas mixture in which the concentration of the first vapor obtained from the non-permeate side of the gas separation membrane module is reduced. Although it is possible to circulate the part, it is possible to suitably use air or an inert gas such as nitrogen gas or argon gas. In addition, the sweep gas is preferably circulated countercurrently to the gas flow on the supply side (non-permeation side) of the separation membrane.

  In the present invention, the pressure adjusting means adjusts the pressure by taking in and out the atmospheric gas. A pressure adjusting valve and a back pressure adjusting valve are arranged, and the pressure is adjusted by a conduit between the pressure adjusting valve and the back pressure adjusting valve. Although the thing connected to the space which should be adjusted is suitable, you may adjust with the pressure regulating valve or electronic pressure regulator provided with the other back pressure adjustment function. Such pressure adjusting means is a simple device, but can adjust the pressure on the non-permeating side with high accuracy.

  In this invention, the atmospheric gas is taken in and out of the separation device as needed from the outside of the separation device in order to adjust the pressure. The pressure is adjusted in advance to a predetermined pressure or higher. A gas that has a boiling point that does not condense in the condenser and is inert to the organic vapor to be separated is suitable, and may be the same gas as the atmospheric gas in the evaporator, for example, air, nitrogen gas, argon gas, etc. The inert gas can be preferably mentioned.

  In this invention, the vapor can exist in the vapor phase and is liquid at 1 atm and −100 ° C., preferably at 1 atm and −50 ° C., and further at 1 atm and 10 ° C. Means that the product has evaporated to a vapor phase when heated above the boiling point. Although not particularly limited, for example, chlorofluorocarbons such as water and freon, perfluoro compounds such as hexafluoroethane, halogenated hydrocarbons such as methylene chloride and chlorobenzene, and nonhalogenated carbons such as benzene, toluene and cyclohexane. Hydrogens, alcohols such as methanol and isopropanol, ketones such as acetone, esters such as ethyl acetate and MEK, phenols such as phenol and cresol, organic acids such as formic acid and acetic acid, amines such as triethylamine and pyridine, Preferable examples include organic solvents such as acetonitrile, dimethylformamide, and N-methyl-2-pyrrolidone.

  The steam mixture is supplied from an industrial process such as a chemical reaction process, a distillation process, a fermentation process, or a cleaning process, such as the chemical industry field, the food field, or the semiconductor field. In some cases, these vapor mixtures can be separated and purified without using a gas separation membrane. However, when the boiling points of the components constituting the vapor mixture are close or azeotropic, a method using a gas separation membrane is preferably employed. The Since the vapor component separated and purified is usually intended to be reused, high purity is required. Therefore, when performing separation and purification with a gas separation membrane, it is important to stabilize the pressure in the separation process so that the gas can be separated and recovered with a specific high purity. Furthermore, in such a separation / purification process, it may be required to prevent a very small amount of impurities from being mixed. If the pressure adjusting means is inserted into a series of flow paths from the evaporator through the gas separation membrane to the purified liquid tank, it is impossible to prevent impurities from being mixed from the drive part of the pressure adjusting means. As in the present invention, it is preferable to adjust the pressure only at the downstream side of the gas separation membrane and at the branched portion, since the contamination of impurities from the drive unit can be eliminated as much as possible.

  In the present invention, the gas separation membrane module comprises a gas separation membrane that can selectively permeate any component of the vapor mixture under the conditions used, a gas supply port, a permeate gas discharge port, and a non-permeate gas discharge port. It is possible to suitably use a container in which the space on the gas separation membrane supply side (non-permeation side) and the permeation side are separated from each other.

  The gas separation membrane may be a flat membrane or the like, but a hollow fiber membrane having a small thickness and a small diameter is suitable because the apparatus can be miniaturized and has a large membrane area, so that the separation efficiency is good and economical. Further, the gas separation membrane may be homogeneous, may be non-uniform such as a composite membrane or an asymmetric membrane, and may be microporous or nonporous. A hollow fiber membrane having a thickness of 10 to 500 μm and an outer diameter of 50 to 2000 μm can be preferably exemplified. Furthermore, it is preferable that the gas separation membrane of the present invention is a gas separation membrane that does not chemically react with the vapor mixture and in which the separation performance is not deteriorated by the vapor mixture. The gas separation membrane is formed of, for example, a polymer material such as polyimide, polyetherimide, polyamide, polyamideimide, polysulfone, polycarbonate, poly (phosphazene), fluorocarbon polymer, silicone resin, cellulose polymer, or ceramic material such as zeolite. In particular, those made of polyimide or a ceramic material are preferable because they have excellent heat resistance and solvent resistance.

A hollow fiber gas separation membrane module using hollow fiber membranes is a bundle of hollow fiber membranes (for example, hundreds to hundreds of thousands) that is bundled into a hollow fiber bundle, and at least one end of the hollow fiber bundle. The hollow fiber separation membrane element is formed by fixing the end part with a curable resin such as an epoxy resin or a thermoplastic resin such as a polyamide resin so that the hollow fiber membrane is in an open state at the end portion. Alternatively, the space leading to the inside of the hollow fiber and the space leading to the outside of the hollow fiber are separated from each other in a container having at least a gas supply port, a permeate gas discharge port, and a non-permeate gas discharge port. It is configured to be mounted as follows.
In this invention, the hollow fiber gas separation membrane module is of the hollow feed type, that is, the hollow fiber separation membrane has a hollow fiber inner space as a supply side (non-permeation side) and a hollow fiber separation membrane outer space as a permeation side. Preferably used.

  The gas separation device of the present invention includes at least an evaporator, a separation membrane module, a condenser, and a pressure regulating tank, and a non-permeate gas discharge port of the separation membrane module is connected to the pressure regulating tank through a condenser, and The pressure regulating tank has pressure adjusting means by taking in and out the atmospheric gas, and is configured to stabilize the supply side pressure of the separation membrane module by the pressure regulating tank having the pressure adjusting means by taking in and out the atmospheric gas. It is a gas separation device characterized by these.

  One embodiment of the gas separation device of the present invention is configured, for example, as shown in the schematic flow chart of FIG. In FIG. 2, the liquid in the stock solution tank 20 is sent by a liquid feed pump 21 to an evaporator 23 having a heater 22. Reference numeral 24 denotes a temperature controller, and 25 denotes a liquid level controller. The liquid amount and temperature in the evaporator 23 are maintained at predetermined values by controlling the liquid feed pump 21 and the heater 22 by the temperature controller 24 and the liquid level controller 25. . The mixed gas containing the vapor mixture generated in the evaporator 23 is overheated by the superheater 26 and then supplied to the gas separation membrane module 29. The temperature of this gas mixture is controlled by a temperature controller 27. The non-permeate flow 31 discharged from the gas separation membrane module 29 is cooled and condensed by the condenser 33, and the vapor component is liquefied and introduced into the pressure regulating tank 34 and stored. The pressure adjusting tank 34 includes pressure adjusting means including an atmospheric gas introduction pipe 35, a pressure adjusting valve 36, and a back pressure adjusting valve 37. A control device is attached to each of the pressure adjustment valve 36 and the back pressure adjustment valve 37, and the pressure on the non-permeate side of the gas separation membrane module 29 communicating with the pressure adjustment tank and the pressure adjustment tank is set in advance. Operates to hold pressure. The permeate stream 30 discharged from the gas separation membrane module 29 is cooled and condensed by the condenser 41, and the vapor component is liquefied, introduced into the permeate tank 42, and stored. Further, the permeation side of the gas separation membrane module 29 is maintained at a predetermined reduced pressure by the exhaust pump 43. A sweep gas is introduced to the permeate side of the gas separation membrane module 29 through the sweep gas introduction pipe 32. The flow rate of the sweep gas is controlled by the flow meter 45.

  The invention is illustrated in more detail by the following examples. In the examples, an example is shown in which high-purity isopropyl alcohol is separated and recovered by dehydrating hydrous isopropyl alcohol having azeotropic properties. In addition, this invention is not limited to an Example.

[Reference Example 1]
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride 100 mol% tetracarboxylic acid component, 4,4′-diaminodiphenyl ether 40 mol%, and 1,4-bis (4-aminophenoxy) Asymmetric hollow fiber membrane made of aromatic polyimide (outer diameter: 500 μm, inner diameter: 310 μm) using an aromatic polyimide solution obtained by polymerizing a diamine component consisting of 60 mol% of benzene, by a dry-wet film forming method Prepared. This asymmetric hollow fiber separation membrane has a water vapor transmission rate of 7.0 × 10 ⁻⁴ cm ³ / cm ² · sec · cm Hg at 120 ° C., and a permeation rate ratio of water vapor to isopropyl alcohol vapor (P _H2O / _Pi-PrOH ) was about 1350. A hollow fiber bundle is prepared using the asymmetric hollow fiber membrane, and both ends of the hollow fiber are cured and bound with a curable resin, the end face is cut, and both ends of each hollow fiber have an effective length of 0.81 m. Create an element so that the gas separation membrane supply side (non-permeate side) and the permeate side space are isolated in a cylindrical container with gas supply port, permeate gas exhaust port, and non-permeate gas exhaust port A gas separation membrane module having an effective membrane area of 5.9 m ² was manufactured by mounting.

[Example 1]
A gas separation apparatus as shown in FIG. 2 equipped with the gas separation membrane module manufactured in Reference Example 1 was prepared, and a mixed liquid composed of 90% by weight of isopropyl alcohol and 10% by weight of water was placed in the stock solution tank. The liquid mixture is supplied to the evaporator with a liquid feed pump, and the heater of the evaporator is set to 255 ° C. at which the necessary amount of evaporation is obtained, and the average amount of evaporation is 18 kg / hour while maintaining the temperature. It was adjusted. The said average flow volume was calculated | required from the weight change of the stock solution tank. The gas mixture containing the vapor mixture evaporated at about 106 ° C. was superheated to about 120 ° C. with a superheater and supplied to the gas separation membrane module.
To the permeate side of the gas separation membrane module, dry nitrogen gas of sweep gas is flowed at 5.0 liter / min in the counterflow direction with respect to the supply gas flow, and the vapor mixture mainly composed of water vapor that has permeated the separation membrane is condensed. Cooled and condensed in a vessel, led to the permeate tank and stored. Further, the permeation side of the gas separation membrane module was evacuated with an exhaust pump provided in the permeate tank and kept at a reduced pressure of 8 kPa (absolute pressure).
The pressure is adjusted by the pressure adjusting means of the pressure adjusting tank, specifically, the pressure is adjusted with nitrogen adjusted to 0.143 MPa (gauge pressure) by the pressure adjusting valve, and the back pressure adjusting valve is set to 0.148 MPa (gauge pressure) to adjust the pressure. Adjustments were made. The non-permeate flow of the gas separation membrane module consists of highly concentrated isopropyl alcohol vapor, which is cooled and condensed by a condenser, liquefied and introduced into a pressure-regulating tank, where it is once stored and purified while adjusting its liquid volume. The solution was sent to the liquid tank.
The supply side pressure of the gas separation membrane module measured with a pressure gauge attached upstream of the gas supply port of the gas separation membrane module was 0.157 MPa (gauge pressure), and the fluctuation range was as small as 0.003 MPa and stable. .
A non-permeate flow condensate was recovered in the purified liquid tank at an average of 16.23 kg / hour. The recovered amount was determined from the change in weight of the purified liquid tank. As a result of periodically taking a sample from between the condenser and the pressure regulator and measuring the moisture with a coulometric titration moisture measuring device, the moisture content was 0.50 ± 0.01 wt%. Isopropyl alcohol having a purity of 99.50% by weight was recovered in the purified liquid tank.

[Example 2]
The pressure is adjusted by the pressure adjusting means of the pressure adjusting tank, specifically, the pressure is adjusted with nitrogen adjusted to 0.165 MPa (gauge pressure) by the pressure adjusting valve, and the setting of the back pressure adjusting valve is set to 0.167 MPa (gauge pressure). The same operation as in Example 1 was performed except that the adjustment was performed.
The supply side pressure of the gas separation membrane module measured with a pressure gauge attached upstream of the gas supply port of the gas separation membrane module was 0.179 MPa (gauge pressure), and the fluctuation range was as small as 0.003 MPa and was stable. .
A non-permeate flow condensate was recovered in the purified liquid tank at an average of 15.42 kg / hour. The recovered amount was determined from the change in the weight of the purified liquid tank. A sample was periodically taken from between the condenser and the pressure regulator, and the moisture content was measured by a coulometric titration moisture measuring device. As a result, the moisture content was 0.42 ± 0.01 wt%. Isopropyl alcohol having a purity of 99.58% by weight was recovered in the purified liquid tank.

Example 3
The same operation as in Example 2 was performed except that the amount of evaporation from the evaporator was adjusted to an average of 9 kg / hour.
The supply side pressure of the gas separation membrane module measured with a pressure gauge attached upstream of the gas supply port of the gas separation membrane module was 0.179 MPa (gauge pressure), and the fluctuation range was as small as 0.003 MPa and was stable. .
A non-permeate condensate was recovered in the purified liquid tank at an average of 8.05 kg / hour. The recovered amount was determined from the change in weight of the purified liquid tank. As a result of periodically taking a sample from between the condenser and the pressure regulator and measuring the moisture with a coulometric titration moisture measuring device, the moisture content was 0.039 ± 0.001 wt%. Isopropyl alcohol having a purity of 99.96% by weight was recovered in the purified liquid tank.

[Comparative Example 1]
FIG. 3 shows a schematic flow diagram in which the pressure-regulating tank provided with the pressure adjusting means is removed from that of Example 1 and the non-permeate flow from the gas separation membrane module is connected to the condenser via the orifice. A separator was used. That is, a gas separation device configured to adjust the pressure on the non-permeate side of the gas separation membrane module with an orifice incorporated in a non-permeate flow line was used.
In the stock solution tank, a mixed solution consisting of 90% by weight of isopropyl alcohol and 10% by weight of water is put, and the mixed solution is supplied to the evaporator by a feed pump, and the heater of the evaporator is heated to 255 ° C. at which a necessary evaporation amount can be obtained. While maintaining the temperature, the average amount of evaporation was adjusted to 18 kg / hour. The said average flow volume was calculated | required from the weight change of the stock solution tank. The gas mixture containing the vapor mixture evaporated at about 102 to 108 ° C. was superheated to 120 ° C. with a superheater and supplied to the gas separation membrane module.
To the permeate side of the gas separation membrane module, dry nitrogen gas of sweep gas is flowed at 5.0 liter / min in the counterflow direction with respect to the supply gas flow, and the vapor mixture mainly composed of water vapor that has permeated the separation membrane is condensed. Cooled and condensed in a vessel, led to the purified liquid tank and stored. Further, the permeation side of the gas separation membrane module was evacuated with an exhaust pump provided in the permeate tank and kept at a reduced pressure of 8 kPa (absolute pressure).
The pressure on the non-permeate side of the gas separation membrane module was set by an orifice. The pressure on the supply side of the gas separation membrane module measured with a pressure gauge attached upstream of the gas supply port of the gas separation membrane module was 0.157 MPa, and the fluctuation range was as large as 0.024 MPa.
A non-permeate flow condensate was recovered in the purified liquid tank at an average of 16.23 kg / hour. The recovered amount was determined from the change in weight of the purified liquid tank. A sample was periodically taken from between the condenser and the purified liquid tank, and the moisture content was measured by a coulometric titration moisture measuring device. As a result, the moisture content was 0.51 ± 0.10% by weight. Isopropyl alcohol having a purity of 99.49% by weight was recovered in the purified liquid tank.

[Comparative Example 2]
The same gas separation apparatus as in Comparative Example 2 was used.
The same operation as in Comparative Example 1 was performed except that a mixed solution consisting of 90% by weight of isopropyl alcohol and 10% by weight of water was placed in the stock solution tank and the amount of evaporation from the evaporator was adjusted to an average of 9 kg / hour. .
The pressure on the non-permeate side of the gas separation membrane module was set by an orifice. The pressure on the supply side of the gas separation membrane module measured with a pressure gauge attached upstream of the gas supply port of the gas separation membrane module was 0.157 MPa (gauge pressure), and the fluctuation range fluctuated as large as 0.023 MPa.
A non-permeate condensate was recovered in the purified liquid tank at an average of 8.05 kg / hour. The recovered amount was determined from the change in weight of the purified liquid tank. A sample was periodically taken from between the condenser and the purified liquid tank, and the moisture content was measured by a coulometric titration moisture measuring device. As a result, the moisture content was 0.06 ± 0.02 wt%. Isopropyl alcohol having a purity of 99.94% by weight was recovered in the purified liquid tank.
Moreover, only the throughput was adjusted at the same pressure and temperature, and the purity of isopropyl alcohol recovered in the purified liquid tank was increased to 99.96% by weight. The amount of evaporation from the evaporator averaged 8 kg / hour, the amount of water was 0.04 ± 0.01% by weight, and non-permeate condensate was recovered in the purified liquid tank at an average of 7.15 kg / hour.

  Although the pressure fluctuation range on the non-permeation side in Examples 1 to 3 was 0.003 MPa and could be stabilized, the pressure fluctuation range on the non-transmission side in Comparative Examples 1 and 2 was 0.023 to 0.024 MPa. It was big. When the pressure fluctuation is large in this way, it is difficult to stabilize the gas separation. For example, when the pressure fluctuation is large, the vaporization temperature of the vapor mixture also fluctuates, so that the temperature control of the evaporator and the superheater is required to have extremely high accuracy. In addition, the purity of the isopropyl alcohol separated and recovered is not so different in the average value when it is operated for a long time, but it changes each time with the pressure fluctuation (in many cases pulsation), so the purified liquid tank frequently When the product is taken out from the container and reused, there is a disadvantage that the purity of the recovered material fluctuates. In Comparative Examples 1 and 2, the gas separation membrane module was operated with the supply side pressure set to 0.157 MPa. However, when the pressure is set higher than this, the pressure may exceed 0.2 MPa due to pressure fluctuation. When the operating pressure exceeds 0.2 MPa, it is necessary to change the pressure resistance required for the apparatus to the high pressure specification by the high pressure gas control method. In an apparatus with a normal pressure resistance specification, the first to third embodiments can be operated at a higher pressure than the first and second comparative examples and can easily achieve high efficiency.

  The present invention generates a vapor mixture from a mixture that may exist in the vapor phase generated from, for example, a chemical reaction process, a distillation process, a fermentation process, a washing process, and the like, and supplies the vapor mixture to a gas separation device including a gas separation membrane module. Separation and recovery can be performed in a stable state while suppressing fluctuations in the pressure on the supply side of the separation membrane module.

Flow chart for explaining the outline of the gas separation method of the present invention Schematic flow diagram of one embodiment of a gas separation device of the invention Schematic flow diagram of the gas separator used in the comparative example

Explanation of symbols

1: Liquid mixture introduction pipe 2: Evaporator 3: Heater 4: Gas mixture stream 5 for drawing a vapor mixture 5: Gas separation membrane module 6: Permeate flow 7: Non-permeate flow 8: Condenser 9: Pressure regulator 10: Pressure adjustment Means 11: Atmospheric gas introduction pipe 12: Pressure adjustment valve 13: Back pressure adjustment valve 14: Conduit 20: Stock solution tank 21: Liquid feed pump 22: Heater 23: Evaporator 24: Temperature controller 25: Liquid level controller 26: Superheater 27: Temperature controller 28: Pressure gauge 29: Gas separation membrane module 30: Permeate flow 31: Non-permeate flow 32: Sweep gas introduction pipe 33: Condenser 34: Pressure regulator 35: Atmospheric gas introduction pipe 36: Pressure regulating valve 37: Back pressure adjusting valve 38: Liquid level controller 39: Valve 40: Purified liquid tank 41: Condenser 42: Permeated liquid tank 43: Exhaust pump (ejector)
44: Pressure gauge 45: Flow meter 46: Sampling port 47: Orifice

Claims (2)

A gas mixture containing the vapor mixture is supplied to the supply side of the gas separation membrane module, and at least the first vapor in the gas mixture containing the vapor mixture is selectively permeated to obtain a permeate flow in which the first vapor has a high concentration and the first flow. In a gas separation method in which one vapor is separated and recovered into a non-permeate flow having a reduced concentration,
The non-permeate flow from the gas separation membrane module is led to a pressure regulating tank through a condenser, and the pressure regulating tank is provided with pressure adjusting means by taking in and out the atmospheric gas, and the pressure adjusting means allows the separation membrane module to A gas separation method characterized by stabilizing a supply-side pressure. A gas mixture containing the vapor mixture is supplied to the supply side of the gas separation membrane module, and at least the first vapor in the gas mixture containing the vapor mixture is selectively permeated to obtain a permeate flow in which the first vapor has a high concentration and the first flow. In a gas separation apparatus that separates and collects a vapor into a non-permeate flow having a reduced concentration,
The non-permeate flow from the gas separation membrane module is led to a pressure regulating tank through a condenser, and the pressure regulating tank is provided with pressure adjusting means by taking in and out the atmospheric gas, and the pressure adjusting means allows the separation membrane module to A gas separation device configured to stabilize a supply-side pressure.

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